1. Field of Invention
The invention is in the field of smoke hoods which have a self-contained oxygen source, and more particularly, relates to a smoke hood that can receive oxygen from a plumbed source and which is switchable to a self-contained oxygen source, by virtue of a new oxygen valve developed for use in the hood.
2. Related Art
Oxygen supply devices are desirable for emergency situations, particularly by crew or passengers in aircraft. Various types of emergency oxygen supply devices are known in the art. A commonly known device consists of a cup-form mask, referred to as a "DIXIE" cup presumably for geometric similarity to a commercial cup so identified under this mark, attached to an oxygen supply tube fixedly connected to a plumbed source of oxygen, such as discussed in Jumpertz U.S. Pat. No. 5,301,665. Such attached devices are restraining, however, because they do not allow a user the freedom to pursue safety or escape. In a life-threatening emergency, it is critical for a user to have the ability to pursue freedom with a portable supply of breathable oxygen that shall last for at least a predetermined amount of time. Devices in the current art for the most part do not address this problem.
Oxygen supply devices in the related art that allow switching from a plumbed source to an independent source of oxygen require two or more distinct steps to switch the source of oxygen. Performing multiple steps in proper sequence, however, is cumbersome and potentially dangerous in a time-critical emergency situation.
Mask type emergency oxygen supply devices are also known in the art, such as Lester U.S. Pat. No. 5,709,204. They usually comprise a mask that covers a user's face, but they do not contain a portable oxygen source. These devices, therefore, typically do not allow two sources of oxygen with a switching mechanism between them. A user is therefore limited to the oxygen available from one oxygen source.
The related art devices have a further drawback of bulkiness. Space on military and civilian aircraft is precious and limited for permanent emergency supplies. On aircraft, especially, there is always a need for dependable emergency equipment comprising lesser volume. Because an emergency oxygen supply device is needed for each passenger, total volume reduction becomes significant when multiplied by the number of passengers.